The present invention relates to a combined chair and bed and, more particularly, to a wheel chair which can be used as or converted into a mobile bed, and vice versa.
There has been known a device which can be used selectively as either a wheel chair or a mobile bed for a patient having a difficulty in walking. The conventional device of this kind, the conventional combined wheel chair and mobile bed, is currently available in two general models. Of these models, one comprises a back rest, a leg support and a seat hinged at one side edge to the back rest and at the opposite side edge to the leg support, said back rest and said leg support being so operatively associated with the seat that, when the back rest is tilted backward, the leg support is pivoted upwards. In this model, when the back rest is completely tilted backwards until it is held in level with the seat, the leg support is also brought to a position level with any one of the seat and the back rest. The reverse movement of the back rest results in conversion of the chair into the bed.
The other model is similar in construction to the first mentioned model, but has a fulcrum about which the seat is temporarily lifted to allow the back rest and the leg support to be substantially held in flush with each other and also with the temporarily lifted seat prior to all of the back rest, the seat and the leg support being subsequently brought to the original position of the seat, that is, the position in level with the level of the seat which has been or will be assumed by the seat when the device is used as a chair.
However, when the combined chair and bed of the first mentioned model is used as a mobile bed for the purpose of transporting a patient from one stationary bed to another in a manner similar to that performed by, or in substitution for, a stretcher, the shift of the patient from the stationary bed to the mobile bed and from the mobile bed to the stationary bed can hardly be carried out with no difficulty because of the difference in height between the seat and the stationary bed.
In order to avoid the above described disadvantage or inconvenience, the design may be employed wherein the seat, when the combined chair and bed is used as a chair, is set at a height equal to the height of the stationary bed which is generally standardized. In the combined chair and bed of this alternative design, since the center of gravity is located at a relatively high position above the floor, it appears to be dangerous and, specifically, the patient steering the wheel chair tends to lose the balance particularly during the turn along a curve.
When it comes to the combined chair and bed of the second mentioned model, the switchover between the chair mode and the bed mode must be carried out while the patient leaves temporarily from the combined chair and bed. More specifically, when the chair mode is desired to be switched over to the bed mode while the patient is sitting on the chair, the weight of the patient exerts a restoration force acting on the seat being upwardly lifted to return the seat to the original position and, therefore, a relatively large pulling force is required to tilt the back rest to a position level with the seat together with the leg support. In addition, when the bed mode is desired to be switched over to the chair mode while the patient is lying on the mobile bed, the back rest, the seat and the leg support are rapidly folded to assume the chair mode by the action of the weight of the patient unless the attendant carefully controls in angularly moving the back rest, once backwardly tilted, to the initial position. The sudden and rapid folding of the assembly to the chair mode will, in many cases, give an adverse effect on the physical and psychological condition of the patient.